The present invention relates to a tool for applying a weldable tape about a bundle of elongate articles and, more particularly, to an improved tool and method for securing the tape about the articles without loss of tension in the tape and without leaving an unsecured loose end or a protruding sharp edge adjacent the weld.
Various techniques exist for bundling elongate articles such as wires, cables or the like. One preferred technique for bundling a plurality of elongate articles involves the feeding of a weldable tape about the bundled articles until the tape overlaps itself, tensioning the tape about the bundle of articles and thereafter welding the tape at the location of the overlap to provide a tensioned loop which secures the bundle of articles. The tensioned loop is then cut free from the remaining stock of tape so that the tool can be removed from the first bundle of articles and moved to a second location to secure a second portion of tape about a second bundle of articles.
The prior art tools accomplish the welding and cutting operations in various ways, all of which have disadvantages. Certain prior art tools are disclosed in U.S. Pat. Nos. 4,265,687, 4,534,817, 5,062,920 and 5,509,994. A first group of prior art tools are configured to both weld and cut the tape at the same location. This technique often results in loosening of the tape about the bundle of articles (i.e., loss of tension) because the cutting portion of the bundling operation may adversely effect and/or weaken the ultrasonic weld which has been previously applied to the tape. Weakening of the weld thus allows the tape to stretch and lose its tension about the bundle of articles. A second group of prior art tools locate the cutting element a distance from the weld location so as not to weaken the weld. These tools, however, leave a loose end of tape adjacent the weld following the cutting operation which is undesirable (and many times unacceptable) in various installations. Certain other prior art tools rely on a technique whereby a portion of the tape is weakened during the welding operation such that the application of tension to the tape following the welding operation severs the tensioned loop tape from the stock of tape. However, the repeatability of such a technique is often inconsistent and, the technique often leaves a ragged loose end adjacent the weld.
There is therefore a need in the art for a tieing tool which can readily bundle a plurality of elongate articles by applying a weldable tape thereabout, tensioning such tape, welding the tensioned loop at the location of the overlap and thereafter severing the welded tensioned loop from the stock of tape without weakening the weld (which allows loss of tension in the bundle of articles) or leaving an unsecured loose end or a protruding sharp edge adjacent the weld which is undesirable and/or unacceptable in various installations.
An additional shortcoming associated with prior art tools is the inability of such tools to both properly feed the tape to the jaws of the tool without jamming and to adequately tension the tape prior to welding. In this regard, prior art tools often experience tape slippage during the tensioning stage of the bundling operation. This is, the tape drive mechanism loses its grip on the tape prior to the proper level of tensioning being achieved in the tape. There is therefore a need in the art for a tieing tool which additionally provides adequate tensioning of the weldable tape during the tensioning stage of the bundling operation, while also providing reliable and efficient tape transfer during the tape advancement stage of the bundling operation.